1. Field of the Invention
This invention relates to a method of eliminating defective parts from a magnetic tape wound on tape winding members such as reels.
2. Background of the Invention
In a Beta or VHS system video tape cassette, 8 mm video tape cassette, or other audio tape cassette, a pair of tape winding members such as reels on which a magnetic tape has been wound are loaded into the cassette. The magnetic tape has leader tapes at both ends, i.e., it is fastened through the leader tapes to the reels. The magnetic tape is spliced to the leader tapes respectively with two pieces of splicing tape (hereinafter referred to as "splicing tape pieces"). The splicing tape pieces are bonded to the rear side of the magnetic tape (opposite to the side where the magnetic layer is formed) so that the tape running operation is smoothly carried out.
However, the junction accuracy of the magnetic tape and each of the leader tape may be low, for instance, in the case where the magnetic tape is butt-joined to the leader tapes for which the junction accuracy as to the gap between the magnetic tape and each of the leader tapes may be low. Such a low junction accuracy may cause a variety of difficulties. In a magnetic tape cassette, the magnetic tape is laid across the front opening of the cassette case. Therefore, during the assembling operation of the cassette, the magnetic tape may be damaged (near the junction of the magnetic tape and the leader tape) by members such as tape guides provided near the front opening. Especially where the magnetic tape cassette manufacturing method is such that a magnetic tape is wound on a pair of reels and then the pair of reels are loaded in the cassette case, the part of the magnetic tape which is disposed at or near the front opening is liable to be damaged. On the other hand, the magnetic tape thickness has been reduced with the development of high-density data recording and reproducing techniques. This further increases the tendency to damage the magnetic tape during the magnetic tape cassette assembling operation.
On the other hand, there is less probability that the leader tape is damaged because it is smaller in thickness than the magnetic tape.
Heretofore, when in a magnetic tape cassette manufacturing operation the above-described defect is found at the tape junction or on the magnetic tape, the magnetic tape cassette is disassembled to elminate the defect, or a manually operated junction jig is used to pull the magnetic tape out of the cassette case without disassembling the cassette to eliminate the defect to thereby make the magnetic tape cassette acceptable. However, the method for eliminating the defect is low in working efficiency because it is practiced substantially manually. Furthermore, the method suffers from a difficulty that secondary troubles are caused which may form another defect during the defect eliminating operation.